<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>built-in function</title>
</head>

<body>
    <script>
        //  1.isNaN
        var name = "Jack";
        console.log(isNaN(name));
        var age = 18;
        console.log(isNaN(age));

        // 2.parseInt integer
        var x = "9";
        console.log(typeof(parseInt(x)));

        // 3.parseFloat
        var y = "3.28";
        console.log(typeof(parseFloat(y)));

        // 4.eval
        var a = 1;
        var b = 2;
        console.log(eval(a + b));

        // 5.prompt
        var inputName = prompt("Enter your Name:", "");
        console.log(inputName);

        // 6.confirm
        var res = confirm("确定退出账号？");
        console.log(res);
        alert(11);
    </script>
</body>

</html>